ABSTRACT
Introduction Iron is a common cofactor in enzymes that employ molecular oxygen as an oxidant. In addition to those iron-dependent enzymes that rely on heme, there is a class of non-heme, mononuclear iron(II) enzymes that catalyze the hydroxylation of aliphatic C-H bonds, dihydroxylation of arene double bonds, epoxidation of C-C double bonds, heterocyclic ring formation, and oxidative aromatic ring opening. e iron in these non-heme dioxygenases is commonly coordinated by a 2-His-1-carboxylate motif [1]. Two histidine (His) and either one aspartic acid (Asp) or one glutamic acid (Glu) residue bind the iron at the vertices of one triangular face of the octahedral metal center, forming a 2-His-1-carboxylate triad of facial ligands (Figure 1A). is arrangement leaves three coordination sites on the iron open for the substrate, oxygen, and other co-substrates.
